Apparatus for manufacturing acid phosphate or superphosphate



W. T. DOYLE.-

APPARATUS FOR MANUFACTURING ACID PHOSPHATE 0R SUPERPHOSPHATE.

APPLICATION FILED MAR. Y3, 1920. 1,883,91 1.,

Patented July 5, 19210 Z SHEETS- SHEET l.

t e w kl/ HJ 5 H mm W 7 9 H /n 1 T I 9\ H a a w 1 7 w a m H 7 n E W 1 3m l/3 7 a T M v w. T. nomz. APPARATUS FOR MANUFACTURING ACID IZ/HOSiHATE0R SUPERPHOSPHATE.

APPLICATION FILED w g. 1a 1920.

1 33 911 I r Patented July 5, 1921.,

2 SHEETS-SHEET 2-' oanrsn stares PATENT orwica;

W ILLIAM DOYLE, 013 BOSTON, MASSACHUSETTS, ASSIGNOR TO STURTEVANT MILLCOMPANY, OF BOSTON, MASSACHUSETTS, A CORPORATION OF MASSACHUSETTS.

APPARATUS FOR MANUFACTURING ACID PHOSPHATE OR SUPERPHOS-PHATE.

esson.

following description, in connection with the accompanying drawings, isa specifica tion, like characters on the drawings representing likeparts.

One important source of acid phosphate is in a phosphate rock which isfound in 7 Florida, Tennesseeand other places. This rock containsphosphoric acid as tribasic phosphate of lime which is insoluble inwater, and consequently when applied to the soil, cannot be assimilatedby plants. Therefore, it is necessary to convert the insolublephosphoric acid in phosphate rock into soluble phosphoric acid. This isaccom-- plished usually by treating the ground rock phosphate withsulfuric acid or hydrochloric acid (usually the former) which removestwo parts of the lime as gypsum and leaves one part .of the limecombined with phosphoric acid as monobasic or acid phosphate of limesoluble in water.

Heretofore, the ground phosphate rock and diluted sulfuric acid, forexample, 1,000 lbs. of each, are introduced into a mixer where themasses are thoroughly mixed and then discharged into a large chambergenerally built of concrete and known as a den. A'chemical reactiontakes place in this den which generates heat, which in turn converts thewater of the diluted sulphuricacid into steam.

Themix'ture is allowed to stand about twelve hours in the den, and thenit is re- -moved and conveyed to acuring pile, where of the purposes ofthe present invention,

therefore, is to provide means for drawing Specification of LettersPatent.

the steam and noxious fumes from the den, so that the workmen may removethe material from the den without injury to them from the poisonousgases.

The acid phosphates coming from the den have a certain percentage offree phosphoric acid which renders them damp and sticky, so that theytend to pack down and solidify. The acid phosphates cannot be sold tothe farmer in this condition, be-

cause they would clog and not pass througha planter or other machine forapplying the phosphates to the soil.' Another purpose of the invention,therefore, is to provide means for removing the moisture from thematerials, so as to render the same indry and pulverulent condition forready application to the soil. In carrying this feature of the inventioninto practical effect, the materials conveyed from the den are broken upand a current of air is passed therethrough so as to come into intimatecontact with the particles and efficiently dry the same.

There is a certain amount of free sulfuric acid in the mixture leavingthe den which has not had time to combine with the phos- Patented July5, 1921.

Application filed March 13, 1920. Serial No. 365,558.

phate of lime so as to be converted into ing finely ground or pulverizedphosphate ro ckto the material taken from the den to combine with thefree sulfuric acid and phosphoric acid, and convert the phosphate oflime into phosphoric acid, thereby materially increasing the amount ofphosphoric acid obtained from the charge of materials introduced intothe den. added finely ground phosphate rock is very much less than thecost of the acid phosphate, so that by the'addition of this finelyground phosphate rock to. the mixture, an importantecono'myis obtainedin the production of the phosphoric acid.

By the apparatus of the present invention, the drying process and theaddition of the finely ground phosphate rock to the mixture coming fromthe den may be continuously carried on, and the insoluble ph0s phoricacid may be'converted into soluble phosphoric acid without the necessityfor allowing the materials to stand a long period in a curing pile toobtain further chemi- The cost of the cal reaction. Heretofore, thematerials needed to stand in the curing pile anywhere from thirty tosixty days, whereas, by the present invention, the materials may be sotreated that they 'will be in readiness for shipment within a shortperiod, such, for

example, as about a week, to allow the same ratus embodying theinvention shown in the accompanying drawings, wherein:.

Figure l is a vertical longitudmal'section through one form of apparatusembodying the invention;

Fig. 2- is a vertlcal transverse section" through the apparatus;

Fig. 3, on an enlarged scale, is a vertical section taken on line 3--3of Fig. 1;

Fig. 4 is a horizontal section taken on line 44 of Fig. 2; and

Figs. 5 and 6 on an enlarged'scale are details of the conveyer.

Referring to the drawings, the apparatus shown therein as embodying theinvention,

comprises a mixer. 1 of usual construction,

into which the ground'phosphate rock and the sulfuric acid may be mixed.

A suitable den. 2 may be provided toreceive the materials from the mixerIn the present instance, this den comprises vertical walls 3 and a roof5 conveniently of concrete one of "the walls having a door? to admit theworkmen intothe den. At the bottom of the den is a fioor9 which may havean elongated opening 11 '(Fig. 3). therein, which may be covered "by aseries of boards 13. 1

Beneath the denis a housing 14 containmg an endless conveyer, 1n thepresent 1nstance,compr1sm a pair of sprocket wheels 15 on a shaft 1 andsprocket wheels 19 ona shaft 21. These sprocket wheels may be connectedby sprocket chains 23- which may carry trough sections 25 of'sufficientlength so as to overlap in the upper horizontal run thereof, and ineffect provide a continuous trough for receiving materials deliveredfrom the den through the elongated opening 11, as more fully hereinafterdescribed. Theupper horizontal runs of .the sprocket chains may beguided by bars 27 supported on frames 29.

After the mixture has remained. in the den for a period, such, forexample, as twenty-four hours, the workmen may enter the den through thedoor Tandprogressively lift the boards 13 on the floor above theelongated 5101311, and by'means of picks terials.

or other suitable means break down the ma- .terials and deliver the same.through'the slot 11 onto the endless conveyer;

As stated, steam and noxious. fumes are generated in the den, and thematerials leave the same in a moist condition. Next will be describedthe means for drawing the steam and noxious fumes from the den, and fordrying the surfaces of the materials as they are conducted from the denby the conveyer.

This means, in the present instance, com-- prises a pipe or conduit 29having one end.

communicating with the housing 14 referred .to, adjacent the deliveryend of the conveyer.

A blower or fan 31 of well known construction may be provided in a box33 communieating withthe pipe 29, said fan being.

driven by a pulley '35 from any suitable source of power. I

The construction is such that on rotation of the fan a suction effectwill be produced in the pipe 29 and the housing 14 which will draw thesteam and noxious fumes from the den and produce anair draft above, i

the materials carried by the conveyer so as to tend to removefmoisturefrom sald ma- The materials delivered from the conveyer are in lump orclosely compact form, and therefore, it is desirable to breakthe same upinto finely divided or pulverulent form. To accomplish this, a hopper37- may be provided having its upper end communicating with the housing14 adjacent the delivery end of the conveyer, so that the materi-. alsmay be delivered by the conveyerinto said hopper. vAt the lower end ofthe hopper 37 is, a device for breaking up the materials,,'conv.eniently in the form of a slicer, in the present instance,comprising blunt arms or bars 39 projecting from a hub 41 fast on avertical shaft 43journaled in bearings" 45 and 47. At the upper end ofsaid shaft is a bevel gear 49 meshing with a bevel gear 51 fast on ahorizontal shaft 53 journaled in bearings 55 and-provided with fast andloose pulleys 57 and 59 for driving the rotary slicer as desired. Thisrotary slicer may be driven at ahighspeedso as to cause the arms 39thereof rapidly to pass the delivery end of the hopper 37 so as to sliceIt is" desirable that a pre-' rock and sulfuric acid introduced into theden is 2,000 lbs., the proportion of pulverulent phosphate rock addedmay desirably be 50 lbs., but this proportion may be varied moreor lesshaving a delivery hopper 63 at the lower end thereof, provided with adischarge mouth 65 and a gate or valve 67 for controlling the dischargefrom said mouth.

- A weighing apparatus may be provided beneath the hopper 63, in-thepresent instance, comprising a weighing receptacle 71 carried adjacentone endof a weighing beam 73 fulcrumed on a support 75 intermediate theends of said beam. A weight 77 may be provided on the beam tocounterbalance the weight of the receptacle 71, and the beam. may beprovided with a poise 79 which may be adjusted-along the beam'todifferent positions according to the weight of pulverulent phosphaterock to be introduced into the weighing receptacle.

Suitable means may be provided to conduct the materials from theweighing receptacle into the delivery end of the housing 1 1 abovethehopper 37. This means, in the present instance, comprises a tube 81containing a screw conveyer 83 which may be rotated by suitable means.In the present instance, this means comprises a ratchet 85 fast onthescrew conveyer shaft 87, and adapted to be advanced step by step bypawls 89 on a pair of arms 91 projectin from the lever 93 fulcrumed onthe sha 87. "The lower end of this lever may be adjustablyconnectedtoone end of a link 95, the opposite end of which may be connected to awrist pin 97 adapted to set in any of a series of holes 99 located atdifferent radial distances from the axis of a disk 101 mountthereonadapted to be driven from any suitable source of power.

The construction is such that a charge of the finely ground phosphaterock to be 7 added may be fed from the weighing receptacle 71 by thescrew conveyer 83 into the delivery end of the housing 14: above thehopper 37. Here it will combine with the materials delivered by thevendless conveyer from the den, and will be mixed with said materials asthey are delivered from said hopper and broken up by the rotary slicer.

Suitable means may be provided for causing a current of air to passthrough the materials delivered from the hopper 37, in ordercontinuously to remove the moisture therefrom. To accomplish this, inthe present instance, a receiving hopper 111 may be provided beneath thehopper 37, and a box 113 may be provided at the upper end of thereceiving hopper. The upper end of this box may be closed and providedwith a door 115 to enable access into the interior thereof. The lowerend 117 of this box may be open, and the wall 119 of .the box may have adiameter less than the mouth of the receivthe annular inlet 121 into thereceiving hopper 111, and thence upward through the box "113 and pipe123. This aircurrent will come in contact with the materials pulverizedby the slicer, and remove moisture therefrom.

The materials may be delivered from the receiving hopper 111 and beconveyed by a car or other suitable means to the place desired, so as tobe in readiness for shipment.

The operation of the apparatus will be readily understood. The finelyground phosphate rock, and the sulfuric acid are introduced in equalparts by weight into the mixer, and delivered therefrom into the den.The materialsareallowed to stand in the den about twenty-four hours toallow the chemical reaction to take place which converts the insolublephosphoric acid into soluble phosphoric acid. 'However, all of theinsoluble phosphoric acid is not converted into soluble phosphoric acidin the den. The workmen may progressively lift the boards 13 and pickdown and deliver the materials from the den through the elongatedpassage 11 to the conveyer. The latter will conduct the materials fromthe den to the hopper 37.

The mixture contains a certain amount of free sulfuric acid which hasnot had sufficient time to combine with the phosphate of lime and beconverted into phosphoric acid, and also contains a certain amount offree phosphoric acid. 1

By the introduction of the dry, finely 110 ground phosphate of lime intothe mixture as it is delivered to the hopper, the free sulfuric acid andphosphoric acid may combine with the finely ground phosphate rock andconvert the latter into phosphori acid. 11; Thus, the percentage ofphosphoric acid obtained from the charge originally intro duced into theden is materially-increased. The value of the added ground phosphaterock is very much less than the value of the 120 acid phosphate, andtherefore, the addition of the ground phosphate rock to utilize the freesulfuric acid and phosphoric acid of the charge effects an importantsaving.

The blower will draw the steam and nox- 125 ious fumes from the denthrough the conveyer housing and away therefrom so as to enable theworkmen to enter the den and pick down and deliver the mixture from theden to the conveyer without discomfort or 130 passing over the mixturebeing conveyed 'will tend to dry the surface portions of the ;mixture,but a substantial amount of moisture still remains in the mixture, whichtends to cause the particles thei eof to adhere together in the 'form oflumps and confine the moistuietherein. It is, therefore, desirable tobreak up or pulverize the mixture delivered from the conveyer, in orderto liberate the moisture therefrom. This is accomplished by the rotaryslicer which operates at a high speed and thoroughly breaks up andpulverizes the materials delivered from the hopper.

The moisture thus liberated is removed from the materials by the currentof air which flows downward through the annular inlet, and thence upwardthrough the box and pipe leading to the blower; This current of aircomes into contact with the materials broken up and'whirled in the boxat the upper end of the hopper,'and effectively removes the liberatedmoisture therefrom. This intensive air treatment of the materials thusbroken up dries the same sufficiently, so that the materials are incondition for shipmentafter they have stood for a few days to allow -thematerials time to cool, since the free sulfuric acid and phosphoric acidhave combined with the finely ground phosphate rock'substantially tocomplete the chemical reaction of the sulfuric acid, the insolublephosphoric acid of the mixture is converted into soluble phosphoric acid"in sufiicient amount, so that it isunnecessaryto transfer the mixtureto a curing pile and allow the same to stand from thirty to sixty daysas has heretofore been necessary, in order to allow the chemicalreactionto be completed, but, on the contrary, the materials are incondition for immediate shipment as soon as cool.

As a consequence, the preparation of the mixture may be substantiallycontinuous, and important economies are obtained. It is unnecessary toprovide a large storage space for the mixture to enable the-chemicalreaction to complete. his unnecessary to transfer the materials from theapparatus to I spirit and scope. of thesappendedclaims.

WVhat is claimed is I 1. An apparatus for manufacturing acid phosphate,comprising, --in means for mixing ground'phosphate rock and sulfuricacid, means-for introducing the mixture into a storage den, means forconveying the mixture from said den, a housing combination,

for said conveying means for communication with said den, means foradding pulverulent phosphate rock to the mixture to take up freesulfuric acid and phosphoric acid in the 'mixture, means to pulverizethe mixture delivered by the conveyer, and means-todraw steam and fumesfrom the den through the housing and also from the pulverizer.

-2. An apparatus for manufacturing acid phosphate, comprising, incombination, a storage-den adapted to receive' a mixture of groundphosphate rock and sulfuric acid, a housing adap ed to communicate withsaid .den, a conveyer in said housing for conducting the mixture fromsaid housing, a pipe communlcatingwith said houslng'and a suction"device for drawing steam and fumes liberated from; the mixture in theden through said housing and pipe.

3. An apparatus for manufacturing acid phosphate, comprising, incombination, a storage den adapted to receive'a mixture ofgroundphospliate rock and sulfuric acid, a housing adapted tocommunicate with said den, a conveyer in said housing. for receiving themixture from'said den and for conducting the same through said housing,means for breaking up the mixture delivered from said conveyer and vaporexhausting means communicating with the breaking means.-

4. An apparatus for. manufacturing acid.

phosphate, comprising, in combination, a storage den adapted to receivea mixture of ground phosphate rock and sulfuric acid, means to break upthe mixture afterleaving said den, means to deliver the materials fromthe den to the means for breaking up the mixture, and means for removingthe moisture from the mixture as' it is broken up.

' 5. An apparatus for manufacturing acid phosphate, comprising, incombination, a

storage den. for receiving a mixture of ground phosphate rock andsulfuric acid, means for deliverlng the mixture from the den, means foradding a percentage of pul-' verulent phosphateroc'kto the mixture afterdelivery of the latter from the den, and means for removing-moisturefrom the mixture.

6. An apparatus for'manufacturing acid phosphate, comprising, incombination, a storage den for receiwing. a mixture'of ground phosphaterock and sulfuric acid, means for delivering the mixture from the den,means for pulverizing the mixture after delivery.thereof from the den,means for adding pulverulent phosphate rock to the' mixture, andmeans'to pass an air current through the pulverized mixture.

. 7. An apparatus for manufacturing acid phosphate, comprising, incombination, a storage den for receiving a mixture of ground phosphaterock and sulfuric acid,

and means including weighing means for adding a predetermined amount ofpulverulent phosphate rock to the mixture after delivery of the latterfrom the den.

8. An apparatus for manufacturing acid phosphate, comprising, incombination, a storage den for receiving a mixture of ground phosphaterockand sulfuric acid, a hopper, means to deliver the mixture from saidden to said hopper, a chamber for receiving pulverulent phosphate rock,Weighing means for receiving the pulverulent phosphate rock from saidchamber, means to feed the phosphate rock from the Weighing means to themixture in the hopper, means to pulverize the mixture, and means toremove vapors liberated during pulverization of the mixture.

9. An apparatus for manufacturing *acid phosphate, comprising, incombination, a

storage den for receiving a mixture of the pulverulent phosphate rockfrom said chamber, a tube leading from said Weighing means to saidhopper, a screw conveyer in said tube, a rotary slicer for breaking upthe mixture delivered from said hopper, a receiving hopper for thematerials broken up by said slicer, 'a suction device, and pipes leadingfrom said suction device to said housing and receiving hopper.

In testimony whereof, I have signed my name to this specification.

. 1AM T. DOYLE.

